const WORLD_SIZE = 1024000;   //世界像素大小
const MERCATOR_RADIOUS = 6378137.0;  //椭圆地球长半轴

module.exports = exports = {
    WORLD_SIZE: WORLD_SIZE,
    PROJECTION_WORLD_SIZE: WORLD_SIZE / (MERCATOR_RADIOUS * Math.PI * 2),//每米多少像素点
    MERCATOR_RADIOUS: MERCATOR_RADIOUS, // 900913 projection property
    DEG2RAD: Math.PI / 180,
    RAD2DEG: 180 / Math.PI,
    EARTH_CIRCUMFERENCE: 40075000, // MERCATOR_RADIOUS * Math.PI * 2    地球周长
}